Package structure and method of fabricating the same

ABSTRACT

A package structure includes a plurality of semiconductor die, an insulating encapsulant and a redistribution layer. Each of the plurality of semiconductor dies includes a semiconductor substrate, conductive pads disposed on the semiconductor substrate, conductive posts disposed on the conductive pads, and at least one alignment mark located on the semiconductor substrate. The insulating encapsulant is encapsulating the plurality of semiconductor dies. The redistribution layer is disposed on the insulating encapsulant and electrically connected to the plurality of semiconductor dies.

BACKGROUND

The semiconductor industry has experienced rapid growth due tocontinuous improvements in the integration density of various electroniccomponents (e.g., transistors, diodes, resistors, capacitors, etc.). Forthe most part, this improvement in integration density has come fromrepeated reductions in minimum feature size, which allows more of thesmaller components to be integrated into a given area. These smallerelectronic components also require smaller packages that utilize lessarea than previous packages. Currently, integrated fan-out packages arebecoming increasingly popular for their compactness. However, there aremany challenges related to integrated fan-out packages.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the criticaldimensions of the various features may be arbitrarily increased orreduced for clarity of discussion.

FIG. 1A and FIG. 1B are schematic sectional views of various stages in amethod of fabricating a semiconductor die in accordance with someembodiments of the present disclosure.

FIG. 2A to FIG. 2G are schematic sectional views of various stages in amethod of fabricating a package structure in accordance with someembodiments of the present disclosure.

FIG. 3 is a schematic sectional view of a package structure inaccordance with some alternative embodiments of the present disclosure.

FIG. 4A to FIG. 4D are schematic top views illustrating variousconfigurations of an alignment mark in accordance with some embodimentsof the present disclosure.

FIG. 5A and FIG. 5B are schematic sectional views of various stages in amethod of fabricating semiconductor dies in accordance with somealternative embodiments of the present disclosure.

FIG. 6A to FIG. 6C are schematic sectional views of various stages in amethod of fabricating a package structure in accordance with somealternative embodiments of the present disclosure.

FIG. 7A and FIG. 7B are schematic sectional views of various stages in amethod of fabricating semiconductor dies in accordance with somealternative embodiments of the present disclosure.

FIG. 8A and FIG. 8B are schematic top views illustrating variousconfigurations of a bulk alignment mark in accordance with someembodiments of the present disclosure.

FIG. 9 is a schematic sectional view of a package structure inaccordance with some alternative embodiments of the present disclosure.

FIG. 10A and FIG. 10B are schematic sectional views of various stages ina method of fabricating semiconductor dies in accordance with somealternative embodiments of the present disclosure.

FIG. 11 is a schematic sectional view of a package structure inaccordance with some alternative embodiments of the present disclosure.

FIG. 12 is a schematic sectional view of a package structure inaccordance with some alternative embodiments of the present disclosure.

FIG. 13A to FIG. 13C are schematic sectional views of various stages ina method of fabricating a package structure in accordance with somealternative embodiments of the present disclosure.

FIG. 14 is a schematic sectional view of a package structure inaccordance with some alternative embodiments of the present disclosure.

FIG. 15 is a schematic top view illustrating the arrangement of packagestructures on a semiconductor wafer in accordance with some embodimentsof the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a second feature over or on a first feature in the description thatfollows may include embodiments in which the second and first featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the second and first features,such that the second and first features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath”, “below”, “lower”,“on”, “over”, “overlying”, “above”, “upper” and the like, may be usedherein for ease of description to describe one element or feature'srelationship to another element(s) or feature(s) as illustrated in thefigures. The spatially relative terms are intended to encompassdifferent orientations of the device in use or operation in addition tothe orientation depicted in the figures. The apparatus may be otherwiseoriented (rotated 90 degrees or at other orientations) and the spatiallyrelative descriptors used herein may likewise be interpretedaccordingly.

Other features and processes may also be included. For example, testingstructures may be included to aid in the verification testing of the 3Dpackaging or 3DIC devices. The testing structures may include, forexample, test pads formed in a redistribution layer or on a substratethat allows the testing of the 3D packaging or 3DIC, the use of probesand/or probe cards, and the like. The verification testing may beperformed on intermediate structures as well as the final structure.Additionally, the structures and methods disclosed herein may be used inconjunction with testing methodologies that incorporate intermediateverification of known good dies to increase the yield and decreasecosts.

FIG. 1A and FIG. 1B are schematic sectional views of various stages in amethod of fabricating a semiconductor die in accordance with someembodiments of the present disclosure. Referring to FIG. 1A, in someembodiments, a first semiconductor die D1 may be formed by the followingsteps. For example, a first semiconductor substrate D1 a is provided.The first semiconductor substrate D1 a may be a bulk silicon substrateor a silicon-on-insulator (SOI) substrate, and further includes activecomponents (e.g., transistors or the like) and optionally passivecomponents (e.g., resistors, capacitors, inductors or the like) formedtherein.

After providing the first semiconductor substrate D1 a, first conductivepads D1 b are formed on the first semiconductor substrate D1 a. Althoughonly one first conductive pad D1 b is illustrated, it is noted that thenumber of first conductive pads D1 b located on the first semiconductorsubstrate D1 a should be more than one. In some embodiments, the firstconductive pads D1 b may be aluminum pads, copper pads or other suitablemetal pads. After forming the first conductive pads D1 b, a firstpassivation layer D1 c is formed over the first semiconductor substrateD1 a, wherein the first passivation layer D1 c has first openings thatpartially expose the first conductive pads D1 b located on the firstsemiconductor substrate D1 a. In some embodiments, the passivation layerD1 c may be a silicon oxide layer, a silicon nitride layer, a siliconoxy-nitride layer or a dielectric layer formed of any suitabledielectric materials. The disclosure is not limited thereto.

In some embodiments, after forming the first passivation layer D1 c,first conductive posts D1 d are formed on the first conductive pads D1 bby plating. For example, the first conductive posts D1 d may be formedby forming a seed layer SD over the first passivation layer D1 c;forming a mask pattern with openings exposing portions of the seed layerSD; forming a metallic material on the exposed portions of the seedlayer SD to form the first conductive posts D1 d by plating; removingthe mask pattern; and then removing portions of the seed layer SDexposed by the first conductive posts D1 d. The remaining seed layer SDwill exist in between the first conductive posts D1 d and the firstconductive pads D1 b.

In some embodiments, a first alignment mark AM1 is formed in the samestep as forming the first conductive posts D1 d. For example, the firstalignment mark AM1 is formed with a seed layer SX1 and a conductive bodyCB1. In some embodiments, the seed layer SX1 and the seed layer SD areformed together in the same steps. In certain embodiments, theconductive body CB1 and the first conductive posts D1 d are formedtogether in the same steps. In some embodiments, the first alignmentmark AM1 and the first conductive posts D1 d are located at the samelevel on the first semiconductor substrate D1 a. Furthermore, the firstalignment mark AM1 and the first conductive posts D1 d are made of thesame materials. In the exemplary embodiment, the first alignment markAM1 is formed with a plurality of stripe patterns. For example, thealignment mark AM1 includes a plurality of stripe patterns when observedfrom a top view. The configuration and design of the stripe patternswill be described in detail later.

Referring to FIG. 1B, in a next step, a first protection layer D1 e isoptionally formed on the first passivation layer D1 c. In someembodiments, the first protection layer D1 e covers the first conductiveposts D1 d and the first alignment mark AM1 so as to protect the firstconductive posts D1 d and the first alignment mark AM1. Dicing may thenbe performed to obtain a plurality of the first semiconductor die D1. Inthe exemplary embodiment, the first semiconductor die D1 may be selectedfrom application-specific integrated circuit (ASIC) chips, analog chips(for example, wireless and radio frequency chips), digital chips (forexample, a baseboard chip), integrated passive devices (IPDs), voltageregulator chips, sensor chips, memory chips, or the like. The disclosureis not limited thereto.

FIG. 2A to FIG. 2G are schematic sectional views of various stages in amethod of fabricating a package structure in accordance with someembodiments of the present disclosure. Referring to FIG. 2A, a carrier102 with a de-bonding layer 104 coated thereon is provided. In someembodiments, the carrier 102 may be a glass carrier or any suitablecarrier for carrying a semiconductor wafer or a reconstituted wafer usedfor the manufacturing method of the package-on-package structure. Insome embodiments, the de-bonding layer 104 may be any material suitablefor bonding and de-bonding the carrier 102 from the above layer(s) orany wafer(s) disposed thereon.

In some embodiments, the de-bonding layer 104 may include a dielectricmaterial layer made of a dielectric material including any suitablepolymer-based dielectric material (such as benzocyclobutene (“BCB”),polybenzoxazole (“PBO”)). In an alternative embodiment, the de-bondinglayer 104 may include a dielectric material layer made of an epoxy-basedthermal-release material, which loses its adhesive property when heated,such as a light-to-heat-conversion (LTHC) release coating film. In afurther alternative embodiment, the de-bonding layer 104 may include adielectric material layer made of an ultra-violet (UV) glue, which losesits adhesive property when exposed to UV lights. In certain embodiments,the de-bonding layer 104 may be dispensed as a liquid and cured, or maybe a laminate film laminated onto the carrier 102. In certainembodiments, the de-bonding layer 104 is, for example, a LTHC layer withgood chemical resistance, and such layer enables room temperaturede-bonding from the carrier 102 by applying laser irradiation.

After providing the carrier 102 and the de-bonding layer 104, a backsideredistribution layer 106 is formed on the de-bonding layer 104. In someembodiments, the backside redistribution layer 106 includes a conductivelayer 106 a embedded within a dielectric layer 106 b. For example, theconductive layer 106 a may be constituted by a plurality ofredistribution conductive patterns. In some embodiments, the dielectriclayer 106 b further includes via openings Vx revealing the conductivelayer 106 a. For simplicity, the dielectric layer 106 b is illustratedas one single layer of dielectric layer and the conductive layer 106 ais illustrated as embedded in the dielectric layer 106 b. However, fromthe perspective of the manufacturing process, the dielectric layer 106 bis constituted by two dielectric layers, and the redistributionconductive layer 106 a is sandwiched between the two adjacent dielectriclayers. In some embodiments, materials of the conductive layer 106 ainclude aluminum, titanium, copper, nickel, tungsten, and/or alloysthereof. The conductive layer 106 a may be formed by, for example,electroplating, deposition, and/or photolithography and etching. In someembodiments, the material of the dielectric layer 106 b includespolyimide, epoxy resin, acrylic resin, phenol resin, benzocyclobutene(BCB), polybenzooxazole (PBO), or any other suitable polymer-baseddielectric material. The dielectric layer 106 b, for example, may beformed by suitable fabrication techniques such as spin-on coating,chemical vapor deposition (CVD), plasma-enhanced chemical vapordeposition (PECVD), or the like.

It should be noted that the number of the conductive layers 106 a andthe number of the dielectric layers 106 b illustrated in FIG. 2A aremerely for illustrative purposes, and the disclosure is not limitedthereto. In some alternative embodiments, more layers of the conductivelayer and more layers of the dielectric layer may be formed depending onthe design requirement. When more layers of conductive layer and morelayers of the dielectric layer are adapted, these conductive layers andthese dielectric layers are stacked alternately, and the conductivelayers are interconnected with one another by the conductive vias.

As illustrated in FIG. 2A, after forming the backside redistributionlayer 106, a plurality of the first semiconductor die D1 prepared inFIG. 1B, and a plurality of through insulator vias 108 are provided onthe backside redistribution layer 106 over the carrier 102. In someembodiments, the through insulator vias 108 are through integratedfan-out (“InFO”) vias. In one embodiment, the formation of the throughinsulator vias 108 includes forming a mask pattern (not shown) withopenings, then forming a metallic material (not shown) filling up theopenings by electroplating or deposition, and removing the mask patternto form the through insulator vias 108 on the backside redistributionlayer 106 and within the via openings Vx. In one embodiment, thematerial of the through insulator vias 108 may include a metal materialsuch as copper or copper alloys, or the like. However, the disclosure isnot limited thereto. In an alternative embodiment, the through insulatorvias 108 may be formed by forming a seed layer (not shown) on thebackside redistribution layer 106; forming the mask pattern withopenings exposing portions of the seed layer; forming the metallicmaterial on the exposed portions of the seed layer to form the throughinsulator vias 108 by plating; removing the mask pattern; and thenremoving portions of the seed layer exposed by the through insulatorvias 108. For example, the seed layer may be a titanium/coppercomposited layer.

Furthermore, as illustrated in FIG. 2A, a plurality of the firstsemiconductor dies D1 is placed on the backside redistribution layer106. Although only two semiconductor dies are illustrated, it should benoted that the number of semiconductor dies placed on the backsideredistribution layer 106 is not limited thereto, and this can beadjusted based on design requirement. In some embodiments, the firstsemiconductor dies D1 are attached or adhered on the backsideredistribution layer 106 through a die attach film (DAF), an adhesionpaste (not shown) or the like. In certain embodiments, the firstsemiconductor die D1 is placed onto the carrier 102, and an alignmentprocess is performed using the first alignment mark AM1 for alignment.Since each of the first semiconductor dies D1 includes at least onealignment mark (first alignment mark AM1), the relative positions ofeach of the first semiconductor dies D1 can be appropriately controlled,and the overlay accuracy of the package structure can be improved.

In the exemplary embodiment, the plurality of first semiconductor diesD1 placed on the backside redistribution layer 106 may be arranged in anarray, and when the first semiconductor dies D1 are arranged in anarray, the through insulator vias 108 may be classified into groups. Thenumber of the first semiconductor dies D1 may correspond to the numberof the groups of the through insulator vias 108. In the illustratedembodiment, the first semiconductor dies D1 may be picked and placed onthe backside redistribution layer 106 after the formation of the throughinsulator vias 108. However, the disclosure is not limited thereto. Insome alternative embodiments, the first semiconductor dies D1 may bepicked and placed on the backside redistribution layer 106 before theformation of the through insulator vias 108.

Referring to FIG. 2B, after forming the through insulator vias 108 andproviding the first semiconductor dies D1, an insulating material 110 isformed on the backside redistribution layer 106 covering the throughinsulator vias 108 and the first semiconductor dies D1. In someembodiments, the insulating material 110 is formed through, for example,a compression molding process, filling up the gaps between the firstsemiconductor dies D1 and adjacent through insulator vias 108 toencapsulate the first semiconductor dies D1. The insulating material 110also encapsulates the through insulator vias 108. In some embodiments,the first conductive posts D1 d and the first protection layer D1 e ofthe first semiconductor dies D1 are encapsulated by and well protectedby the insulating material 110. In other words, the first conductiveposts D1 d and the first protection layer D1 e are not revealed and arewell protected by the insulating material 110.

In some embodiments, the insulating material 110 includes polymers (suchas epoxy resins, phenolic resins, silicon-containing resins, or othersuitable resins), dielectric materials having low permittivity (Dk) andlow loss tangent (Df) properties, or other suitable materials. In analternative embodiment, the insulating material 110 may include anacceptable insulating encapsulation material. In some embodiments, theinsulating material 110 may further include inorganic filler orinorganic compound (e.g. silica, clay, and so on) which can be addedtherein to optimize coefficient of thermal expansion (CTE) of theinsulating material 110. The disclosure is not limited thereto.

Referring to FIG. 2C, in a next step, the insulating material 110 andthe first protection layer D1 e of the first semiconductor dies D1 areground or polished by a mechanical grinding process and/or a chemicalmechanical polishing (CMP) process until the top surfaces D1 d-TS of thefirst conductive posts D1 d and the top surfaces AM1-TS of the firstalignment mark AM1 are revealed. In some embodiments, the throughinsulator vias 108, the first conductive posts D1 d and the firstalignment mark AM1 may be partially polished so that the top surface108-TS of the through insulator vias 108 are levelled with the topsurfaces D1 d-TS of the first conductive posts D 1 d and the topsurfaces AM1-TS of the first alignment mark AM1. The insulating material110 is polished to form an insulating encapsulant 110′. In someembodiments, after the polishing process, a top surface 110-TS of theinsulating encapsulant 110′ is coplanar with the top surface 108-TS ofthrough insulator vias 108, the top surface D1 d-TS of the firstconductive posts D1 d and the top surface AM1-TS of the first alignmentmark AM1.

Referring to FIG. 2D, after forming the insulating encapsulant 110′, aredistribution layer 112 is formed on the first semiconductor die DE onthe through insulator vias 108, and on the insulating encapsulant 110′.In some embodiments, the redistribution layer 112 is formed on the topsurface 108-TS of the through insulator vias 108, on the top surface D1d-TS of the first conductive posts D1 d, and on the top surface 110-TSof the insulating encapsulant 110′. In some embodiments, theredistribution layer 112 is electrically connected to the throughinsulator vias 108, and is electrically connected to the firstsemiconductor dies D1 through the first conductive posts D1 d. Incertain embodiments, the first semiconductor dies D1 are electricallyconnected to the through insulator vias 108 through the redistributionlayer 112.

In some embodiments, the formation of the redistribution layer 112includes sequentially forming one or more dielectric layers 112 a, andone or more conductive layers 112 b in alternation. In certainembodiments, the conductive layers 112 b are sandwiched between thedielectric layers 112 a. For example, a first dielectric layer 112 a-1is formed over the insulating encapsulant 110′, and the first dielectriclayer 112 a-1 has contact openings revealing the first conductive postsD1 d. Subsequently, a first conductive layer 112 b-1 is formed withinthe contact openings and over the first dielectric layer 112 a-1.Thereafter, a second dielectric layer 112 a-2, a second conductive layer112 b-2 and a third dielectric layer 112 a-3 are sequentially formed inthe same way. Although only two layers of the conductive layers 112 band three layers of dielectric layers 112 a are illustrated herein,however, the scope of the disclose is not limited by the embodiments ofthe disclosure. In other embodiments, the number of conductive layers112 b and the dielectric layers 112 a may be adjusted based on productrequirement. In some embodiments, seed layers SY are formed prior toforming the conductive layers 112 b. In other words, the firstconductive layer 112 b-1 and the second conductive layer 112 b-2 arerespectively formed on a seed layer SY. In some embodiments, theconductive layers 112 b are electrically connected to the conductiveposts D1 d of the first semiconductor dies D 1. Furthermore, theconductive layers 112 b are electrically connected to the throughinsulator vias 108.

In certain embodiments, the material of the dielectric layers 112 a maybe polyimide, polybenzoxazole (PBO), benzocyclobutene (BCB), a nitridesuch as silicon nitride, an oxide such as silicon oxide, phosphosilicateglass (PSG), borosilicate glass (BSG), boron-doped phosphosilicate glass(BPSG), a combination thereof or the like, which may be patterned usinga photolithography and/or etching process. In some embodiments, thedielectric layers 112 a are formed by suitable fabrication techniquessuch as spin-on coating, chemical vapor deposition (CVD),plasma-enhanced chemical vapor deposition (PECVD) or the like. Thedisclosure is not limited thereto.

In some embodiments, the material of the conductive layer 112 b may bemade of conductive materials formed by electroplating or deposition,such as aluminum, titanium, copper, nickel, tungsten, and/or alloysthereof, which may be patterned using a photolithography and etchingprocess. In some embodiments, the conductive layer 112 b may bepatterned copper layers or other suitable patterned metal layers.Throughout the description, the term “copper” is intended to includesubstantially pure elemental copper, copper containing unavoidableimpurities, and copper alloys containing minor amounts of elements suchas tantalum, indium, tin, zinc, manganese, chromium, titanium,germanium, strontium, platinum, magnesium, aluminum or zirconium, etc.

After forming the redistribution layer 112, a plurality of conductivepads 112 c may be disposed on an exposed top surface of the topmostlayer of the conductive layers 112 b (second conductive layer 112 b-2)for electrically connecting with conductive balls. In certainembodiments, the conductive pads 112 c are for example, under-ballmetallurgy (UBM) patterns used for ball mount. As shown in FIG. 2D, theconductive pads 112 c are formed on and electrically connected to theredistribution layer 112. In some embodiments, the materials of theconductive pads 112 c may include copper, nickel, titanium, tungsten, oralloys thereof or the like, and may be formed by an electroplatingprocess, for example. The number of conductive pads 112 c are notlimited in this disclosure, and may be selected based on the designlayout. In some alternative embodiments, the conductive pads 112 c maybe omitted. In other words, conductive balls 114 formed in subsequentsteps may be directly disposed on the redistribution layer 112.

As illustrated in FIG. 2D, after forming the conductive pads 112 c, aplurality of conductive balls 114 is disposed on the conductive pads 112c and over the redistribution layer 112. In some embodiments, theconductive balls 114 may be disposed on the conductive pads 112 c by aball placement process or reflow process. In some embodiments, theconductive balls 114 are, for example, solder balls or ball grid array(BGA) balls. In some embodiments, the conductive balls 114 are connectedto the redistribution layer 112 through the conductive pads 112 c. Incertain embodiments, some of the conductive balls 114 may beelectrically connected to the first semiconductor dies D1 through theredistribution layer 112. Furthermore, some of the conductive balls 114may be electrically connected to the through insulator vias 108 throughthe redistribution layer 112. The number of the conductive balls 114 isnot limited to the disclosure, and may be designated and selected basedon the number of the conductive pads 112 c. In some alternativeembodiments, an integrated passive device (IPD) (not shown) mayoptionally be disposed on the redistribution layer 112 and beelectrically connected to the redistribution layer 112.

Referring to FIG. 2E, in a next step, after forming the redistributionlayer 112 and the conductive balls 114, the structure shown in FIG. 2Emay be turned upside down and attached to a tape 201 supported by aframe 202. Subsequently, the carrier 102 is debonded so as to separatethe de-bonding layer 104 and the other elements formed thereon from thecarrier 102. In the exemplary embodiment, the de-bonding processincludes projecting a light such as a laser light or an UV light on thede-bonding layer 104 (e.g., the LTHC release layer), such that thecarrier 102 can be easily removed. In certain embodiments, thede-bonding layer 104 may be further removed or peeled off to reveal thebackside redistribution layer 106.

Referring to FIG. 2F, in a next step, the dielectric layer 106 b of thebackside redistribution layer 106 may be patterned to form a pluralityof openings that expose the conductive layers 106 a. Thereafter, aplurality of conductive balls 120 may be placed on the surface of theconductive layers 106 a exposed by the openings. The conductive balls120 are, for example, reflowed to bond with the surfaces of theconductive layers 106 a. Referring to FIG. 2G, the structure illustratedin FIG. 2F is diced or singulated along the dicing lanes DL to form aplurality of package structures PK1. In some embodiments, the dicingprocess or the singulation process typically involves dicing with arotating blade or a laser beam. In other words, the dicing orsingulation process is, for example, a laser cutting process, amechanical cutting process, or other suitable processes. Up to here, apackage structure PK1 having dual side terminals is accomplished.

FIG. 3 is a schematic sectional view of a package structure inaccordance with some alternative embodiments of the present disclosure.The package structure PK2 illustrated in FIG. 3 is similar to thepackage structure PK1 illustrated in FIG. 2G, hence the same referencenumerals are used to refer to the same or liked parts, and its detaileddescription will be omitted herein. The difference between theembodiment shown in FIG. 3 and the embodiment of FIG. 2G is that thefirst protection layer D1 e is omitted from some of the firstsemiconductor dies D1. In other words, the insulating encapsulant 110′is in direct contact with the first alignment mark AM1 and the firstconductive posts D1 d. Similar to the embodiment above, since each ofthe first semiconductor dies D1 includes at least one alignment mark(first alignment mark AM1), the relative positions of each of the firstsemiconductor dies D1 can be appropriately controlled, and the overlayaccuracy of the package structure can be improved.

FIG. 4A to FIG. 4D are schematic top views illustrating variousconfigurations of an alignment mark in accordance with some embodimentsof the present disclosure. In the embodiments of the present disclosure,the alignment mark having stripe patterns may be any one of the designsshown in FIG. 4A to FIG. 4D. In other words, the first alignment markAM1 illustrated in the package structure PK1 and the package structurePK2 may be designed to have the stripe patterns shown in FIG. 4A to FIG.4D. Referring to FIG. 4A, the stripe patterns 301 may have stripes ofdifferent lengths, and the stripe patterns 301 are extending along afirst direction X1 and sequentially arranged along a second direction X2that is perpendicular to the first direction X1. In some embodiments,the stripe patterns 301 are arranged to form an alignment mark AM with aL-shaped grid pattern. In some embodiments, the alignment mark AM has adimension of 1 μm to 20 μm. Herein, the dimension refers to the lengthor the width of the alignment mark AM from the top view. By adapting thealignment mark AM with the stripe patterns, the signal noise on thealignment mark AM may be sufficiently reduced. That is, the machinery isable to precisely detect the alignment mark AM, thereby enhancing theoverlay accuracy and reducing the alignment failure rate. For example,in some embodiments, an overlay accuracy within 0.5 μm may be achievedthrough the adaption of the stripe patterns.

In some alternative embodiments, the alignment mark AM may have othershapes from the top view. For example, referring to FIG. 4B, the stripepatterns 301 together form a square-shaped grid pattern. Thesquare-shaped grid pattern has an L-shaped hollow portion therein. Insome embodiments, the machinery may detect the contour of the L-shapedhollow portion based on the stripe patterns 301 for alignment. FIG. 4Aand FIG. 4B illustrated that all of the stripe patterns 301 in thealignment mark AM are separated from each other, but the disclosure isnot limited thereto. For example, referring to FIG. 4C, the stripepatterns 301 having stripes of different lengths may be connected toform a hollow polygonal shape. In some embodiments, the stripe patterns301 may be connected to each other to form a L-shaped pattern.Furthermore, referring to FIG. 4D, in some embodiments, a portion of thestripe patterns 301 may be connected to each other to form a firstL-shaped pattern. On the other hand, another portion of the stripepatterns 301 are connected to each other to form a second L-shapedpattern encircling the first L-shaped pattern. As illustrated in FIG.4D, the stripe patterns 301 in the first L-shaped pattern are separatedfrom the stripe patterns 301 in the second L-shaped pattern. By adaptingthe alignment marks AM of the present disclosure with the stripepatterns, the signal noise on the alignment mark AM may be sufficientlyreduced and the overlay accuracy may be sufficiently enhanced.

FIG. 5A and FIG. 5B are schematic sectional views of various stages in amethod of fabricating semiconductor dies in accordance with somealternative embodiments of the present disclosure. Referring to FIG. 5Aand FIG. 5B, a first semiconductor die D1 and a second semiconductor dieD2 is fabricated. The first semiconductor die D1 is fabricated in thesame way as described in FIG. 1A and FIG. 1B, hence its detaileddescription will be omitted herein. In the exemplary embodiment, thefirst semiconductor die D1 and the second semiconductor die D2 aredifferent types of semiconductor dies. For example, in some embodiments,the first semiconductor die D1 may be an application-specific integratedcircuit (“ASIC”) die, and the second semiconductor die D2 may be a highbandwidth memory (HBM) die, the disclosure is not limited thereto.

The method of fabricating the second semiconductor die D2 is as follows.For example, a second semiconductor substrate D2 a is provided. Thesecond semiconductor substrate D2 a may be a bulk silicon substrate or asilicon-on-insulator (SOI) substrate, and further includes activecomponents (e.g., transistors or the like) and optionally passivecomponents (e.g., resistors, capacitors, inductors or the like) formedtherein.

After providing the second semiconductor substrate D2 a, secondconductive pads D2 b are formed on the second semiconductor substrate D2a. Although only one second conductive pad D2 b is illustrated, it isnoted that the number of second conductive pads D2 b located on thesecond semiconductor substrate D2 a should be more than one. In someembodiments, the second conductive pads D2 b may be aluminum pads,copper pads or other suitable metal pads. After forming the secondconductive pads D2 b, a second passivation layer D2 c is formed over thesecond semiconductor substrate D2 a, wherein the second passivationlayer D2 c has second openings that partially expose the secondconductive pads D2 b located on the second semiconductor substrate D2 a.In some embodiments, the second passivation layer D2 c may be a siliconoxide layer, a silicon nitride layer, a silicon oxy-nitride layer or adielectric layer formed of any suitable dielectric materials. Thedisclosure is not limited thereto.

In some embodiments, after forming the second passivation layer D2 c,second conductive posts D2 d are formed on the second conductive pads D2b by plating. For example, the second conductive posts D2 d may beformed by forming a seed layer SD over the second passivation layer D2c; forming a mask pattern with openings exposing portions of the seedlayer SD; forming a metallic material on the exposed portions of theseed layer SD to form the second conductive posts D2 d by plating;removing the mask pattern; and then removing portions of the seed layerSD exposed by the second conductive posts D2 d. The remaining seed layerSD will exist in between the second conductive posts D2 d and the secondconductive pads D2 b.

In some embodiments, a second alignment mark AM2 is formed in the samestep of forming the second conductive posts D2 d. For example, thesecond alignment mark AM2 is formed with a seed layer SX2 and aconductive body CB2. In some embodiments, the seed layer SX2 and theseed layer SD are formed together in the same steps. In certainembodiments, the conductive body CB2 and the second conductive posts D2d are formed together in the same steps. In some embodiments, the secondalignment mark AM2 and the second conductive posts D2 d are located atthe same level on the second semiconductor substrate D2 a. Furthermore,the second alignment mark AM2 and the second conductive posts D2 d aremade of the same materials. In the exemplary embodiment, the secondalignment mark AM2 is formed with a plurality of stripe patterns. Forexample, the second alignment mark AM2 includes a plurality of stripepatterns when observed from a top view. In certain embodiments, thefirst alignment mark AM1 and the second alignment mark AM2 may be anyone of the designs shown in FIG. 4A to FIG. 4D. In one embodiment, thefirst alignment mark AM1 and the second alignment mark AM2 may have thesame design or configuration. In an alternative embodiment, the firstalignment mark AM1 and the second alignment mark AM2 may have differentdesign or configuration.

Referring to FIG. 5B, in a next step, a first protection layer D1 e isoptionally formed on the first passivation layer D1 c, wherein the firstprotection layer D1 e covers the first conductive posts D1 d and thefirst alignment mark AM1 in the first semiconductor die D1. On the otherhand, the second conductive posts D1 d and the second alignment mark AM2in the second semiconductor die D2 are not covered by any protectionlayer. That is, the second conductive posts D1 d and the secondalignment mark AM2 are revealed. Dicing may then be performed to obtaina plurality of the first semiconductor dies D1 and a plurality of secondsemiconductor dies D2

FIG. 6A to FIG. 6C are schematic sectional views of various stages in amethod of fabricating a package structure in accordance with somealternative embodiments of the present disclosure. The method offabricating the package structure shown in FIG. 6A to FIG. 6C is similarto the method shown in FIG. 2A to FIG. 2G, hence the same referencenumerals are used to refer to the same or liked parts, and its detaileddescription will be omitted herein. The difference between theembodiments is that the first semiconductor die D1 and the secondsemiconductor die D2 prepared in FIG. 5B are used instead.

Referring to FIG. 6A, at least one first semiconductor die D1 and onesecond semiconductor die D2 prepared in FIG. 5B, and a plurality ofthrough insulator vias 108 are provided on the backside redistributionlayer 106 over the carrier 102. In some embodiments, a plurality ofthrough insulator vias 108 are provided on the backside redistributionlayer 106 to surround the first semiconductor die D1 and the secondsemiconductor die D2. Although only two semiconductor dies areillustrated herein, it should be noted that the number of semiconductordies placed on the backside redistribution layer 106 is not limitedthereto, and this can be adjusted based on design requirement. In someembodiments, the first semiconductor die D1 and the second semiconductordie D2 are attached or adhered on the backside redistribution layer 106through a die attach film (DAF), an adhesion paste (not shown) or thelike. In some embodiments, the first semiconductor die D1 is placed ontothe carrier 102, and a first alignment process is performed using thefirst alignment mark AM1 for alignment. In certain embodiments, thesecond semiconductor die D2 is placed onto the carrier 102, and a secondalignment process is performed using the second alignment mark AM2 foralignment.

After forming the through insulator vias 108 and providing the firstsemiconductor die D1 and the second semiconductor die D2, an insulatingmaterial 110 is formed on the backside redistribution layer 106 to coverthe through insulator vias 108, the first semiconductor die D1 and thesecond semiconductor die D2. In some embodiments, the insulatingmaterial 110 is formed to encapsulate the first semiconductor die D1 andthe second semiconductor die D2. Since a protection layer is omittedfrom the second semiconductor die D2, the insulating material 110 isformed to be in direct contact with the second conductive posts D2 d andthe second alignment mark AM2. Furthermore, the insulating material 110also encapsulates the through insulator vias 108.

Referring to FIG. 6B, after forming the insulating material 110, theinsulating material 110 is polished to form an insulating encapsulant110′. Thereafter, the same steps described in FIG. 2D may be performedto form the redistribution layer 112, the conductive pads 112 c and theconductive balls 114. In some embodiments, the redistribution layer 112is electrically connected to the first conductive posts D1 d of thefirst semiconductor die D1, and electrically connected to the secondconductive posts D2 d of the second semiconductor die D2. Furthermore,the redistribution layer 112 may be electrically connected to thethrough insulator vias 108 by the conductive layers 112 b.

Referring to FIG. 6C, in a next step, the carrier 102 is debonded so asto separate the de-bonding layer 104 and the other elements formedthereon from the carrier 102. Subsequently, the dielectric layer 106 bof the backside redistribution layer 106 may be patterned to form aplurality of openings that expose the conductive layers 106 a, and aplurality of conductive balls 120 may be placed on the surface of theconductive layers 106 a exposed by the openings. The structure may thenbe diced or singulated to form a plurality of package structures PK3.Similar to the embodiments above, since each of the first semiconductordie D1 and the second semiconductor die D2 includes at least onealignment mark (first alignment mark AM1 and second alignment mark AM2)used for the alignment process, the relative positions of the firstsemiconductor die D1 to the second semiconductor die D2 can beappropriately controlled, and the overlay accuracy of the packagestructure can be improved.

FIG. 7A and FIG. 7B are schematic sectional views of various stages in amethod of fabricating semiconductor dies in accordance with somealternative embodiments of the present disclosure. Referring to FIG. 7Aand FIG. 7B, a first semiconductor die Dl and a second semiconductor dieD2 is fabricated. The method of fabricating the first semiconductor dieD1 and the second semiconductor D2 is similar to the method described inFIG. 5A and FIG. 5B, hence the same reference numerals will be used torefer to the same or liked parts, and its detailed description will beomitted herein. The difference being that the second semiconductor dieD2 of FIG. 7A and FIG. 7B is fabricated with a bulk alignment mark BAM.

The method of fabricating the second semiconductor die D2 is as follows.Referring to FIG. 7A, a second semiconductor substrate D2 a is provided.After providing the second semiconductor substrate D2 a, secondconductive pads D2 b are formed on the second semiconductor substrate D2a. Subsequently, a second passivation layer D2 c is formed over thesecond semiconductor substrate D2 a, wherein the second passivationlayer D2 c has second openings that partially expose the secondconductive pads D2 b located on the second semiconductor substrate D2 a.

In some embodiments, after forming the second passivation layer D2 c,second conductive posts D2 d are formed on the second conductive pads D2b by plating. Furthermore, in some embodiments, a bulk alignment markBAM is formed in the same step of forming the second conductive posts D2d on the second passivation layer D2 c. For example, the bulk alignmentmark BAM is formed with a seed layer SX3 and a conductive body CB3. Insome embodiments, the seed layer SX3 and the seed layer SD are formedtogether in the same steps. In certain embodiments, the conductive bodyCB3 and the second conductive posts D2 d are formed together in the samesteps. In some embodiments, the bulk alignment mark BAM and the secondconductive posts D2 d are located at the same level on the secondsemiconductor substrate D2 a. Furthermore, the bulk alignment mark BAMand the second conductive posts D2 d are made of the same materials. Inthe exemplary embodiment, a “bulk” alignment mark tends to mean that thealignment mark can be viewed primarily as a single mass of material, andit does not have stripe patterns.

Referring to FIG. 7B, in a next step, a second alignment mark AM2 havinga plurality of stripe patterns is formed on the second passivation layerD2 c. In some embodiments, the second alignment mark AM2 is formed afterforming the second conductive posts D2 c and the bulk alignment markBAM. In certain embodiments, the second alignment mark AM2 is formedwith a seed layer SX2 and a conductive body CB2. Furthermore, the secondalignment mark AM2, the bulk alignment mark BAM and the secondconductive posts D2 d are located at the same level on the secondsemiconductor substrate D2 a. In some embodiments, during the formationof the second alignment mark AM2, the bulk alignment mark BAM is furtheretched to form an undercut Ux. In certain embodiments, the seed layerSX3 of the bulk alignment mark BAM is etched to form the undercut Ux.After forming the second alignment mark AM2, dicing may then beperformed to form a plurality of the second semiconductor die D2.

FIG. 8A and FIG. 8B are schematic top views illustrating variousconfigurations of a bulk alignment mark in accordance with someembodiments of the present disclosure. The design of the bulk alignmentmark BAM illustrated in FIG. 7A and FIG. 7B is not particularly limited,and can be for example, any one of the designs shown in FIG. 8A and FIG.8B. Referring to FIG. 8A, the bulk alignment mark BAM is formed with aL-shaped pattern. Referring to FIG. 8B, the bulk alignment mark BAM isformed with a polygonal shape. However, the bulk alignment marks BAM ofFIG. 8A and FIG. 8B are formed as a single mass of material, and doesnot contain any stripe patterns.

FIG. 9 is a schematic sectional view of a package structure inaccordance with some alternative embodiments of the present disclosure.The package structure PK4 illustrated in FIG. 9 is similar to thepackage structure PK3 illustrated in FIG. 6C, hence the same referencenumerals are used to refer to the same or liked parts, and its detaileddescription will be omitted herein. The difference between theembodiments is that the first semiconductor die Dl and the secondsemiconductor die D2 prepared in FIG. 7B are used instead. In otherwords, the second semiconductor die D2 further contains the bulkalignment mark BAM with the undercut Ux. Similar to the embodimentsabove, since each of the first semiconductor die D1 and the secondsemiconductor die D2 includes at least one alignment mark (firstalignment mark AM1 and second alignment mark AM2) used for the alignmentprocess, the relative positions of the first semiconductor die D1 to thesecond semiconductor die D2 can be appropriately controlled, and theoverlay accuracy of the package structure can be improved.

FIG. 10A and FIG. 10B are schematic sectional views of various stages ina method of fabricating semiconductor dies in accordance with somealternative embodiments of the present disclosure. Referring to FIG. 10Aand FIG. 10B, a first semiconductor die D1 and a second semiconductordie D2 is fabricated. The method of fabricating the first semiconductordie D1 and the second semiconductor D2 is similar to the methoddescribed in FIG. 5A and FIG. 5B, hence the same reference numerals willbe used to refer to the same or liked parts, and its detaileddescription will be omitted herein. The difference between theembodiments is in the position of the first alignment mark AM1 and thesecond alignment mark AM2.

Referring to FIG. 10A, in the first semiconductor die D1, the firstalignment mark AM1 and the first conductive pads D1 b are formedtogether in the same steps. In some embodiments, the first alignmentmark AM1 and the first conductive pads D1 b are located at the samelevel on the first semiconductor substrate D 1 a. Furthermore, the firstalignment mark AM1 and the first conductive pads D1 b are made of thesame materials. Similarly, in the second semiconductor die D2, thesecond alignment mark AM2 and the second conductive pads D2 b are formedtogether in the same steps. In some embodiments, the second alignmentmark AM2 and the second conductive pads D2 b are located at the samelevel on the second semiconductor substrate D2 a. Furthermore, thesecond alignment mark AM2 and the second conductive pads D2 b are madeof the same materials. In the exemplary embodiment, the first alignmentmark AM1 and the second alignment mark AM2 are formed with a pluralityof stripe patterns. For example, the first alignment mark AM1 and thesecond alignment mark AM2 may be any one of the designs shown in FIG. 4Ato FIG. 4D.

Referring to FIG. 10B, in a next step, a first protection layer D1 e anda second protection layer D2 e are optionally formed on the firstpassivation layer D1 c and the second passivation layer D2 crespectively. In some embodiments, the first protection layer D1 ecovers the first conductive posts D1 d and the first alignment mark AM1in the first semiconductor die D1. In certain embodiments, the secondprotection layer D2 e covers the second conductive posts D2 d and thesecond alignment mark AM2 in the second semiconductor die D2. In someembodiments, since the first protection layer D1 e and the secondprotection layer D2 e are made of transparent materials, the firstalignment mark AM1 covered by the first protection layer D1 e, and thesecond alignment mark AM2 covered by the second protection layer D2e canstill be observed, detected and used for alignment. After forming thefirst protection layer D1 e and the second protection layer D2 e, dicingmay then be performed to form a plurality of the first semiconductordies D1 and a plurality of the second semiconductor dies D2.

FIG. 11 is a schematic sectional view of a package structure inaccordance with some alternative embodiments of the present disclosure.The package structure PK5 illustrated in FIG. 11 is similar to thepackage structure PK3 illustrated in FIG. 6C, hence the same referencenumerals are used to refer to the same or liked parts, and its detaileddescription will be omitted herein. The difference between theembodiments is that the first semiconductor die D1 and the secondsemiconductor die D2 prepared in FIG. 10B are used instead. In otherwords, the first alignment mark AM1 and the first conductive pads D1 bare located at the same level on the first semiconductor substrate D1 a.Furthermore, the second alignment mark AM2 and the second conductivepads D2 b are located at the same level on the second semiconductorsubstrate D2 a. Similar to the embodiments above, since each of thefirst semiconductor die D1 and the second semiconductor die D2 includesat least one alignment mark (first alignment mark AM1 and secondalignment mark AM2) used for the alignment process, the relativepositions of the first semiconductor die D1 to the second semiconductordie D2 can be appropriately controlled, and the overlay accuracy of thepackage structure can be improved.

FIG. 12 is a schematic sectional view of a package structure inaccordance with some alternative embodiments of the present disclosure.The package structure PK6 illustrated in FIG. 12 is similar to thepackage structure PK5 illustrated in FIG. 11 , hence the same referencenumerals are used to refer to the same or liked parts, and its detaileddescription will be omitted herein. The difference between theembodiments is in the position of the second alignment mark AM2. In theabove embodiments, the position of the alignment mark (AM1/AM2) on thesemiconductor substrate is the same for the first semiconductor die D1and the second semiconductor die D2. However, the disclosure is notlimited thereto. Referring to FIG. 12 , in the first semiconductor dieD1, the first alignment mark AM1 and the first conductive pads D1 b arelocated at the same level on the first semiconductor substrate D1 a,whereas in the second semiconductor die D2, the second alignment markAM2 and the second conductive posts D2 d are located at the same levelon the second semiconductor substrate D2 a. In other words, thealignment marks (AM1/AM2) may be located at the pad-level or at thepost-level depending on actual design requirements. Similar to theembodiments above, since each of the first semiconductor die D1 and thesecond semiconductor die D2 includes at least one alignment mark (firstalignment mark AM1 and second alignment mark AM2) used for the alignmentprocess, the relative positions of the first semiconductor die D1 to thesecond semiconductor die D2 can be appropriately controlled, and theoverlay accuracy of the package structure can be improved.

FIG. 13A to FIG. 13C are schematic sectional views of various stages ina method of fabricating a package structure in accordance with somealternative embodiments of the present disclosure. The method offabricating the package structure PK7 shown in FIG. 13C is similar tothe method of fabricating the package structure PK3 as described in FIG.6A to FIG. 6C. Therefore, the same reference numerals are used to referto the same or liked parts, and its detailed description will be omittedherein. The difference between the embodiments is that auxiliaryalignment marks AAM are further formed on the redistribution layer 112.

Referring to FIG. 13A, the redistribution layer 112 is formed by firstforming a first dielectric layer 112 a-1 having contact openingsrevealing the first conductive posts D1 d and the second conductiveposts D2 d. Subsequently, a first conductive layer 112 b-1 is formedwithin the contact openings and over the first dielectric layer 112 a-1.In the exemplary embodiment, auxiliary alignment marks AAM are formed inthe same steps of forming the first conductive layer 112 b-1. In certainembodiments, the auxiliary alignment marks AAM are formed with a seedlayer SZ and a conductive body CX. In some embodiments, the seed layerSZ and the seed layer SY are formed together in the same steps.Furthermore, the conductive body CX and the first conductive layer 112b-1 are formed together in the same steps, and the conductive body CXand the first conductive layer 112 b-1 are made of the same materials.In the exemplary embodiment, the auxiliary alignment marks AAM areformed with a plurality of stripe patterns. For example, the auxiliaryalignment marks AAM may be any one of the designs shown in FIG. 4A toFIG. 4D.

Referring to FIG. 13B, in a next step, a second dielectric layer 112a-2, a second conductive layer 112 b-2 and a third dielectric layer 112a-3 are sequentially formed in the same way as in FIG. 6B. Thereafter,the same steps described in FIG. 2D may be performed to form theconductive pads 112 c and the conductive balls 114 on the redistributionlayer 112. In the exemplary embodiment, the auxiliary alignment marksAAM are only formed on the first dielectric layer 112 a-1. However, thedisclosure is not limited thereto, in some other embodiments, theauxiliary alignment marks AAM may be formed on any of the firstdielectric layer 112 a-1, the second dielectric layer 112 a-2 and/or thethird dielectric layer 112 a-3.

Referring to FIG. 13C, in a next step, the carrier 102 is debonded so asto separate the de-bonding layer 104 and the other elements formedthereon from the carrier 102. Subsequently, the dielectric layer 106 bof the backside redistribution layer 106 may be patterned to form aplurality of openings that expose the conductive layers 106 a, and aplurality of conductive balls 120 may be placed on the surface of theconductive layers 106 a exposed by the openings. The structure may thenbe diced or singulated to form a plurality of package structures PK7.Similar to the embodiments above, since each of the first semiconductordie D1 and the second semiconductor die D2 includes at least onealignment mark (first alignment mark AM1 and second alignment mark AM2),the relative positions of the first semiconductor die D1 to the secondsemiconductor die D2 can be appropriately controlled, and the overlayaccuracy of the package structure can be improved. Furthermore, byforming the redistribution layer 112 having the auxiliary alignmentmarks AAM, the subsequently formed elements may be accurately formed onthe designated location with high overlay accuracy, thereby enhancingthe reliability of the package structure.

FIG. 14 is a schematic sectional view of a package structure inaccordance with some alternative embodiments of the present disclosure.The package structure PK8 illustrated in FIG. 14 is similar to thepackage structure PK7 illustrated in FIG. 13C, hence the same referencenumerals are used to refer to the same or liked parts, and its detaileddescription will be omitted herein. The difference between theembodiments is that the backside redistribution layer 106 is omittedfrom FIG. 14 . In the above embodiments, all of the first semiconductordies D1 and the second semiconductor dies D2 are bonded onto thebackside redistribution layer 106. However, the disclosure is notlimited thereto. Referring to FIG. 14 , the first semiconductor die D1and the second semiconductor die D2 are bonded onto a dielectric layer104. In some embodiments, the dielectric layer 104 may be patterned toform a plurality of openings that expose the through insulator vias 108.Thereafter, a plurality of conductive balls 120 may be placed on thesurface of the through insulator vias 108 exposed by the openings. Assuch, a package structure PK8 having dual side terminals isaccomplished.

As illustrated in FIG. 14 , since each of the first semiconductor die D1and the second semiconductor die D2 includes at least one alignment mark(first alignment mark AM1 and second alignment mark AM2) used for thealignment process, the relative positions of the first semiconductor dieD1 to the second semiconductor die D2 can be appropriately controlled,and the overlay accuracy of the package structure can be improved.Furthermore, by forming the redistribution layer 112 having theauxiliary alignment marks AAM, the subsequently formed elements may beaccurately formed on the designated location with high overlay accuracy,thereby enhancing the reliability of the package structure.

FIG. 15 is a schematic top view illustrating the arrangement of packagestructures on a semiconductor wafer in accordance with some embodimentsof the present disclosure. Referring to FIG. 15 , each of the packagestructures prepared in the above embodiments may be fabricated on asemiconductor wafer. For example, the semiconductor wafer may be dicedto form a plurality of package structures PK. In the exemplaryembodiment, the number of semiconductor dies disposed on each of thepackage structure PK is not limited thereto, and this can be adjustedbased on design requirement. For instance, in one embodiment, a packagestructure PK may contain two semiconductor dies Dx being the same typeof semiconductor dies. In another embodiment, a package structure PK maycontain a first semiconductor die Dx, a second semiconductor die Dy anda third semiconductor die Dz, wherein these semiconductor dies aredifferent types of semiconductor dies. Since each of the semiconductordies (Dx, Dy or Dz) in the package structure PK respectively includes atleast one alignment mark AM used for alignment, the semiconductor diesDx may be picked and placed on the semiconductor wafer with high overlayaccuracy and reduced field shift error.

In the above-mentioned embodiments, each of semiconductor dies in thepackage structure includes at least one alignment mark, therefore, therelative positions of the semiconductor dies (die to die position) canbe appropriately controlled, and the overlay accuracy of the packagestructure can be improved. As such, the semiconductor dies may be pickedand placed on the semiconductor wafer with high overlay accuracy andreduced field shift error.

In some embodiments of the present disclosure, a package structureincludes a plurality of semiconductor die, an insulating encapsulant anda redistribution layer. Each of the plurality of semiconductor diesincludes a semiconductor substrate, conductive pads disposed on thesemiconductor substrate, conductive posts disposed on the conductivepads, and at least one alignment mark located on the semiconductorsubstrate. The insulating encapsulant is encapsulating the plurality ofsemiconductor dies. The redistribution layer is disposed on theinsulating encapsulant and electrically connected to the plurality ofsemiconductor dies.

In another embodiment of the present disclosure, a package structureincludes a first semiconductor die, a second semiconductor die, aninsulating encapsulant and a redistribution layer. The firstsemiconductor die includes a first semiconductor substrate, firstconductive pads disposed on the first semiconductor substrate, firstconductive posts disposed on the first conductive pads, and a firstalignment mark located on the first semiconductor substrate, the firstalignment mark includes first stripe patterns. The second semiconductordie includes a second semiconductor substrate, second conductive padsdisposed on the semiconductor substrate, second conductive postsdisposed on the second conductive pads, and a second alignment marklocated on the second semiconductor substrate, the second alignment markof the second semiconductor die includes second stipe patterns. Theinsulating encapsulant is encapsulating the first semiconductor die andthe second semiconductor die. The redistribution layer is disposed onthe insulating encapsulant and electrically connected to the firstsemiconductor die and the second semiconductor die.

In yet another embodiment of the present disclosure, a method offabricating a package structure is described. The method includes thefollowing steps. A first semiconductor substrate having first conductivepads formed thereon is provided. A first passivation layer with firstopenings is formed over the first conductive pads. First conductiveposts are formed within the first openings and over the first conductivepads. First alignment mark is formed to be located on the firstpassivation layer. Dicing is performed to obtain first semiconductordies. A second semiconductor die is provided. The second semiconductordie has a second semiconductor substrate having second conductive padsformed thereon, a second passivation layer covering the secondconductive pad and having a second opening exposing the secondconductive pads, second conductive posts disposed on the secondconductive pads within the second opening, and a bulk alignment marklocated on the second passivation layer. A second alignment mark isformed on the second passivation layer, wherein the bulk alignment markis etched to form an undercut during forming the second alignment mark.The first semiconductor die is placed onto a carrier, and a firstalignment process is performed using the first alignment mark foralignment. The second semiconductor die is placed beside the firstsemiconductor die, and a second alignment process is performed using thesecond alignment mark for alignment. An insulating encapsulant is formedover the carrier and encapsulating the first semiconductor die and thesecond semiconductor die. A redistribution layer is formed on theinsulating encapsulant, wherein the redistribution layer is electricallyconnected to the first semiconductor die and the second semiconductordie.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A package structure, comprising: a firstsemiconductor die and a second semiconductor die, wherein the firstsemiconductor die and the second semiconductor die respectivelycomprises a semiconductor substrate, conductive pads disposed on thesemiconductor substrate, conductive posts disposed on the conductivepads, and an alignment mark located on the semiconductor substrate, andwherein a protection layer is covering and contacting the alignment markof the first semiconductor die; an insulating encapsulant encapsulatingthe first semiconductor die and the second semiconductor die, whereinthe insulating encapsulant is in physical contact with the alignmentmark of the second semiconductor die, and is physically separated fromthe alignment mark of the first semiconductor die by the protectionlayer, and wherein a top surface of the insulating encapsulant iscoplanar with a top surface of the conductive posts and a top surface ofthe alignment marks of the first semiconductor die and the secondsemiconductor die; and a redistribution layer disposed on the topsurface the insulating encapsulant and electrically connected to theconductive posts of the first semiconductor die and the secondsemiconductor die, the redistribution layer comprises: a firstdielectric layer disposed on the insulating encapsulant, covering andcontacting the alignment marks of the first semiconductor die and thesecond semiconductor die, wherein the first dielectric layer comprises aplurality of openings revealing the top surface of the conductive postsof the first semiconductor die and the second semiconductor die; a firstseed layer disposed on and in physical contact with the first dielectriclayer, wherein the first seed layer fills into the plurality of openingsto be physically and electrically connected to the conductive posts ofthe first semiconductor die and the second semiconductor die; a firstconductive layer disposed on the first seed layer; auxiliary alignmentmarks comprising an auxiliary seed layer and a conductive body disposedon the auxiliary seed layer, wherein the auxiliary alignment markscomprise a plurality of stripe patterns, and wherein a thickness of theauxiliary seed layer is equal to a thickness of the first seed layer,the first dielectric layer is physically contacting a bottom surface ofthe auxiliary seed layer, and a top surface of the conductive body isaligned with a top surface of the first conductive layer; and a seconddielectric layer disposed on the first dielectric layer and in physicalcontact with the first dielectric layer, wherein the second dielectriclayer is surrounding the first seed layer, the first conductive layerand the auxiliary alignment marks, and wherein the second dielectriclayer is covering and physically contacting the top surface of theconductive body and the top surface of the first conductive layer. 2.The package structure according to claim 1, wherein the alignment markand the conductive posts of the first semiconductor die are located atthe same level on the semiconductor substrate, and the alignment markand the conductive posts of the first semiconductor die are made of thesame materials.
 3. The package structure according to claim 1, whereinthe alignment mark of the first semiconductor die comprises a pluralityof stripe patterns.
 4. The package structure according to claim 3,wherein the first semiconductor die and the second semiconductor die aredifferent types of semiconductor dies.
 5. The package structureaccording to claim 4, wherein the second semiconductor die comprises abulk alignment mark disposed on the semiconductor substrate of thesecond semiconductor die, and the bulk alignment mark has an undercut.6. The package structure according to claim 1, wherein the auxiliaryalignment marks and the first conductive layer are made of the samematerial.
 7. The package structure according to claim 1, wherein thefirst semiconductor die further comprises a passivation layer disposedon and in physical contact with the semiconductor substrate andpartially covering the conductive pads, and the alignment mark of thefirst semiconductor die includes a seed layer and a conductive bodylocated on the seed layer, and the seed layer is in physical contactwith the passivation layer.
 8. The package structure according to claim1, wherein the auxiliary alignment marks comprise two auxiliaryalignment marks located near edges of the redistribution layer.
 9. Apackage structure, comprising: a first semiconductor die comprising afirst semiconductor substrate, first conductive pads disposed on thefirst semiconductor substrate, first conductive posts disposed on thefirst conductive pads, a first alignment mark located on the firstsemiconductor substrate, the first alignment mark comprises first stripepatterns, and a protection layer in physical contact with and coveringthe first conductive posts and the first alignment mark, wherein a topsurface of the first conductive posts is leveled with a top surface ofthe protection layer; a second semiconductor die comprising a secondsemiconductor substrate, second conductive pads disposed on the secondsemiconductor substrate, second conductive posts disposed on the secondconductive pads, and a second alignment mark located on the secondsemiconductor substrate, the second alignment mark of the secondsemiconductor die comprises second stripe patterns; an insulatingencapsulant encapsulating the first semiconductor die and the secondsemiconductor die, wherein the insulating encapsulant is in physicalcontact with the second conductive posts and the second alignment markof the second semiconductor die, and is physically separated from thefirst conductive posts and the first alignment mark of the firstsemiconductor die by the protection layer; a redistribution layerdisposed on a top surface the insulating encapsulant and electricallyconnected to the first semiconductor die and the second semiconductordie; and a backside redistribution layer disposed on a bottom surface ofthe insulating encapsulant, wherein the first conductive posts, thefirst conductive pads and the first alignment mark of the firstsemiconductor die, the second conductive posts, the second conductivepads and the second alignment mark of the second semiconductor die, andthe insulating encapsulant are located in between inner surfaces of theredistribution layer and the backside redistribution layer.
 10. Thepackage structure according to claim 9, wherein the first alignment markand the first conductive posts are located at the same level on thefirst semiconductor substrate, and the first alignment mark and thefirst conductive posts are made of the same materials.
 11. The packagestructure according to claim 9, wherein the second alignment mark andthe second conductive posts are located at the same level on the secondsemiconductor substrate, and the second alignment mark and the secondconductive posts are made of the same materials.
 12. The packagestructure according to claim 9, wherein the first stripe patterns aredifferent than the second stripe patterns.
 13. The package structureaccording to claim 9, wherein the second semiconductor die comprises abulk alignment mark disposed on the second semiconductor substrate ofthe second semiconductor die, the bulk alignment mark has an undercut,and the bulk alignment mark and the second alignment mark are located atthe same level on the second semiconductor substrate.
 14. The packagestructure according to claim 9, wherein the redistribution layercomprises a plurality of dielectric layers and a plurality of conductivelayers alternately stacked, and an auxiliary alignment mark disposed ona bottommost dielectric layer of the plurality of dielectric layers, andthe auxiliary alignment mark comprises a plurality of stripe patterns.15. The package structure according to claim 9, wherein the first stripepatterns or the second stripe patterns have stripes of differentlengths, and the stripes of different lengths are extending along afirst direction and sequentially arranged along a second direction thatis perpendicular to the first direction.
 16. The package structureaccording to claim 9, wherein the first stripe patterns or the secondstripe patterns have stripes of different lengths, and the stripes ofdifferent lengths are connected to form a hollow polygonal shapepattern.
 17. The package structure according to claim 9, furthercomprising conductive balls disposed on and electrically connected tothe redistribution layer and the backside redistribution layer.
 18. Amethod of fabricating a package structure, comprising: providing a firstsemiconductor substrate having first conductive pads thereon; forming afirst passivation layer with first openings revealing the firstconductive pads; forming first conductive posts within the firstopenings and over the first conductive pads; forming a first alignmentmark located on the first passivation layer; forming a protection layerin physical contact with and covering the first conductive posts and thefirst alignment mark; performing dicing to obtain first semiconductordies; providing a second semiconductor die, wherein the secondsemiconductor die has a second semiconductor substrate having secondconductive pads thereon, a second passivation layer covering the secondconductive pads and having a second opening exposing the secondconductive pads, second conductive posts disposed on the secondconductive pads within the second opening, and a bulk alignment marklocated on the second passivation layer; and forming a second alignmentmark on the second passivation layer, wherein the bulk alignment mark isetched to form an undercut during forming the second alignment mark;placing the first semiconductor die onto a backside redistribution layerover a carrier and performing a first alignment process using the firstalignment mark for alignment; placing the second semiconductor diebeside the first semiconductor die and performing a second alignmentprocess using the second alignment mark for alignment; forming aninsulating material over the carrier covering the first semiconductordie and the second semiconductor die, wherein the backsideredistribution layer is disposed on a bottom surface of the insulatingmaterial; performing a planarization step on the insulating material toform an insulating encapsulant encapsulating the first semiconductor dieand the second semiconductor die, wherein after the planarization step,a top surface of the first conductive posts is leveled with a topsurface of the protection layer, and wherein the insulating encapsulantis in physical contact with the second conductive posts and the secondalignment mark of the second semiconductor die, and is physicallyseparated from the first conductive posts and the first alignment markof the first semiconductor die by the protection layer; and forming aredistribution layer on a top surface of the insulating encapsulant,wherein the redistribution layer is electrically connected to the firstsemiconductor die and the second semiconductor die, and wherein thefirst conductive posts, the first conductive pads and the firstalignment mark of the first semiconductor die, the second conductiveposts, the second conductive pads and the second alignment mark of thesecond semiconductor die, and the insulating encapsulant are located inbetween inner surfaces of the redistribution layer and the backsideredistribution layer.
 19. The method of fabricating the packagestructure according to claim 18, wherein the forming of theredistribution layer comprises: forming a first dielectric layer overthe insulating encapsulant, wherein the first dielectric layer hascontact openings revealing the first conductive posts and the secondconductive posts; forming a first conductive layer within the contactopenings and over the first dielectric layer; and forming an auxiliaryalignment mark on the first dielectric layer, wherein the auxiliaryalignment mark and the first conductive layer are formed in the samesteps.